1. Field of the Invention
This invention relates to a bolt or pin retention device for releasably securing a bolt or pin within an aperture in a support structure. Pin retention devices are used in a variety of environments, particularly heavy duty machinery in which pin-connected parts are subjected to high stress during use.
2. Description of the Prior Art
In U.S. Pat. No. 2,543,148 there is disclosed a shaft or pin locking mechanism wherein a bar is welded or otherwise secured to a yoke and prevents a shaft disposed within the yoke from moving outwardly therefrom. The shaft has a notched pin head which abuts against the bar and a cotter pin is placed through the head to prevent the shaft from being removed in the other direction from the yoke. Such a pin locking mechanism, while completely retaining the pin from one end thereof, is disadvantageous because the cotter pins are susceptible to breakage after a certain number of repeated uses. A cotter key when inserted through a hole in a pin must have its end portions bent around the pin in order to prevent the cotter key from sliding out.
In U.S. Pat. No. 2,862,314 there is disclosed a drag hitch assembly in which a shackle pin is secured within a hitch plate by means of an upwardly extending arcuate wall which is disposed over a retainer plate. The retainer plate is secured to a hitch by means of a bolt. The shackle is equipped with an enlarged head which bears downwardly against the bottom wall of a recess provided in the uppermost portion of the hitch. U.S. Pat. No. 2,862,314 does not disclose or suggest a pin having a head with a notch wherein a drive lock plate is inserted between the pin and a retaining means to retain the pin completely from one end.
A lock member constructed of a molded rubber head used in conjunction with a locking pin or key is described in U.S. Pat. No. 3,126,654. The locking pin has a corrugated surface which interconnects with a plurality of metal inserts on the lock member. This particular structure is used to lock an excavating tooth onto an adapter, but there is no suggestion of using the locking pin and lock member to secure a pin having a notch into a hole. Also, there is no use of a retainer as is set forth in the present invention.
Another prior art patent of interest is U.S. Pat. No. 2,455,125. Here, there is disclosed a lock nut which has a recess provided in the nut body so that a resilient means retained in the recess will be engaged by the threads of a bolt and flexed thereby to create a frictional drag which substantially resists unloosening of the nut.
In U.S. Pat. No. 3,572,785 there is shown a wedge employed to secure an adapter and lip of a power shovel. Placed in a recess of the wedge is a pad of resilient material. A locking member which is undulated serves to connect a shovel lip and an adapter to form a connection therebetween. While one form of the present invention utilizes a locking plate with grooves which engage a plug, U.S. Pat. No. 3,572,785 does not provide for a retaining means used in conjunction with a bolt or pin having a notched head.
Spring bias is used to prevent lateral movement of a plate with respect to a bolt in U.S. Pat. No. 325,221. However, this patent does not set forth the novel structure of the present invention which uses a spring to bias a plug against a lock plate which is in turn biased against a bolt having a notched head.